Torsten Römer Torsten Römer - 2 months ago 49
Android Question

CONNECTIVITY_ACTION intent received twice when Wifi connected

In my app I have a

BroadcastReceiver
that is launched as a component through a
<receiver>
tag, filtering
android.net.conn.CONNECTIVITY_CHANGE
intents.

My goal is simply to know when a Wifi connection was established, so what I am doing in
onReceive()
is this:

NetworkInfo networkInfo = intent.getParcelableExtra(ConnectivityManager.EXTRA_NETWORK_INFO);
if(networkInfo.getType() == ConnectivityManager.TYPE_WIFI && networkInfo.isConnected()) {
// Wifi is connected
}


It works fine, but I always seem to get two identical intents within about one second when a Wifi connection is established. I tried to look at any info I could get from the intent, the
ConnectivityManager
and
WifiManager
, but I can't find anything that distinguishes the two intents.

Looking at the log, there is at least one other
BroadcastReceiver
that also receives the two identical intents.

It is running on a HTC Desire with Android 2.2

Any idea why I seem to get a "duplicated" intent when Wifi connects or what the difference between the two might be?

Answer

After a lot of googling and debugging, I believe this is the correct way to determine if Wifi has connected or disconnected.

The onReceive() method in the BroadcastReceiver:

public void onReceive(final Context context, final Intent intent) {

if(intent.getAction().equals(WifiManager.NETWORK_STATE_CHANGED_ACTION)) {
    NetworkInfo networkInfo =
        intent.getParcelableExtra(WifiManager.EXTRA_NETWORK_INFO);
    if(networkInfo.isConnected()) {
        // Wifi is connected
        Log.d("Inetify", "Wifi is connected: " + String.valueOf(networkInfo));
    }
} else if(intent.getAction().equals(ConnectivityManager.CONNECTIVITY_ACTION)) {
    NetworkInfo networkInfo =
        intent.getParcelableExtra(ConnectivityManager.EXTRA_NETWORK_INFO);
    if(networkInfo.getType() == ConnectivityManager.TYPE_WIFI &&
        ! networkInfo.isConnected()) {
        // Wifi is disconnected
        Log.d("Inetify", "Wifi is disconnected: " + String.valueOf(networkInfo));
    }
}
}

Together with the following receiver element in AndroidManifest.xml

<receiver android:name="ConnectivityActionReceiver"
    android:enabled="true" android:label="ConnectivityActionReceiver">
    <intent-filter>
        <action android:name="android.net.conn.CONNECTIVITY_CHANGE"/>
        <action android:name="android.net.wifi.STATE_CHANGE"/>
    </intent-filter>
</receiver>

Some explanation:

  • When only considering ConnectivityManager.CONNECTIVITY_ACTION, I always get two intents containing identical NetworkInfo instances (both getType() == TYPE_WIFI and isConnected() == true) when Wifi connects - the issue described in this question.

  • When only using WifiManager.NETWORK_STATE_CHANGED_ACTION, there is no intent broadcasted when Wifi disconnects, but two intents containing different NetworkInfo instances, allowing to determine one event when Wifi is connected.

NOTE: I've received one single crash report (NPE) where the intent.getParcelableExtra(ConnectivityManager.EXTRA_NETWORK_INFO) returned null. So, even if it seems to be extremely rare to happen, it might be a good idea to add a null check.

Cheers, Torsten

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